diff --git a/src/lib/analytics/score/__tests__/config-delta-guard.test.ts b/src/lib/analytics/score/__tests__/config-delta-guard.test.ts
index 4eff8ddfc..c9609b154 100644
--- a/src/lib/analytics/score/__tests__/config-delta-guard.test.ts
+++ b/src/lib/analytics/score/__tests__/config-delta-guard.test.ts
@@ -403,11 +403,23 @@ describe("the seam", () => {
   });
 
   it("treats a day that names no recipe as a break rather than a link", () => {
-    const points = scoreSeriesSeams([
-      day("2026-08-19", null),
-      day("2026-08-20", 1),
-    ]);
-    expect(points[1].seamBreak).toBe(true);
+    // Both directions, including two unknowns in a row. Without the
+    // second case the arm would be doing nothing that plain inequality
+    // does not already do: `null !== 1` breaks on its own, while
+    // `null !== null` would quietly claim two rows share a basis that
+    // neither of them names.
+    expect(
+      scoreSeriesSeams([day("2026-08-19", null), day("2026-08-20", 1)])[1]
+        .seamBreak,
+    ).toBe(true);
+    expect(
+      scoreSeriesSeams([day("2026-08-19", 1), day("2026-08-20", null)])[1]
+        .seamBreak,
+    ).toBe(true);
+    expect(
+      scoreSeriesSeams([day("2026-08-19", null), day("2026-08-20", null)])[1]
+        .seamBreak,
+    ).toBe(true);
   });
 
   it("breaks the composite line and never rejoins it", () => {
diff --git a/src/lib/analytics/score/composite.ts b/src/lib/analytics/score/composite.ts
index dd2b61cda..3522d8d47 100644
--- a/src/lib/analytics/score/composite.ts
+++ b/src/lib/analytics/score/composite.ts
@@ -235,17 +235,19 @@ function comparableDynamicPillars(
  *
  * No date means nothing to compare, and that does not suppress:
  * refusing every delta forever over an unreadable timestamp would trade
- * one silent lie for a permanent silence.
+ * one silent lie for a permanent silence. Both cases — an account that
+ * never chose, and a stored date this build cannot read — parse to NaN,
+ * and every comparison against NaN is false, so the refusal falls out
+ * of the arithmetic. Two early returns stood here and neither could
+ * change an answer, which makes them a comment wearing an `if`.
  */
 export function crossesConfigBoundary(
   boundary: ScoreConfigBoundary,
   previousAt: Date,
   asOf: Date,
 ): boolean {
-  if (boundary.changedAt === null) return false;
-  const changedAt = new Date(boundary.changedAt);
-  if (Number.isNaN(changedAt.getTime())) return false;
-  return asOf >= changedAt && previousAt < changedAt;
+  const changedAt = Date.parse(boundary.changedAt ?? "");
+  return asOf.getTime() >= changedAt && previousAt.getTime() < changedAt;
 }
 
 /**